Various types of connectors are known that provide low loss coupling of optical fibers. They typically comprise a plug and a receptacle or a plug-adapter-plug arrangement wherein precision mating coaxial components of the connector assembly containing prealigned fibers with optically prepared ends are brought together in the connecting process to achieve alignment and abutment of the mating fibers to within micron tolerances. These mating surfaces are usually covered with protective caps that are removed prior to engagement. The connecting fibers can also be achieved within alignment guides such as that described in U.S. Pat. No. 4,224,214, wherein fibers are coaxially aligned by their own precision outside diameters in a common V-groove or other means. Fiber ends are susceptible to contamination prior to engagement. Various prior art patents address the issue and attempt to provide solutions to reduce the amount of contamination from dirt, debris, grease, and other contaminants, however, this problem continues to exist. In fact, as of late, the effects of contaminants on an end face surface of an optical fiber connector have become an increasingly larger problem than in the past. This is due in part to the fact that high energy optical signals are becoming more commonplace with an increased use of rare-earth doped optical fiber amplifiers. As well, the problem of dirt and debris present at the fiber end face is becoming increasingly more serious with recent requirements to use optical fibers having a small core diameter, i.e. in the range of 6 microns or less. An impetus for utilizing a fiber of this type, having a small mode field diameter (MFD), is a high power density that is desirable for pumping rare earth, (i.e. erbium) doped amplifying optical fiber. However, high power optical energy propagating within a small MFD produces an optical power density at a fiber end face that is excessively high. At times when debris is present at a connector end face and is heated up by this concentrated optical signal, the heated particles scorch, pit, and damage the end face of the optical fiber connector end, rendering it useless for further transmission. The damage to the connector end in some instances is so severe, that is believed that these contaminant particles actually explode in the presence of sufficient concentrated light energy. This problem is known to exist in standard single mode optical fiber having a MFD of about 10 .mu.m with optical signals having about 100 milliwatts of power, and is yet more damaging in instances where these or higher power optical signals are concentrated in a smaller core diameter optical fiber. In practice coupling two optical fibers carrying very high density power signals has required that the optical fiber ends be permanently fused rather than releasably coupled by a connector to obviate this potential hazard caused by debris at a connector end face.
It is an object of this invention to provide a connector that is less vulnerable to dirt and debris at a connector end face in the presence of high power density optical energy.
It is an object of the invention to attempt to overcome some of these known limitations of prior art connectors.